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Alternative Climate Wedges

This page attempts to explore alternative approaches to
climate change mitigation, focused on recognizing and embracing limits to
growth. Your comments and suggestions are greatly appreciated!

Note the six sub-pages below, where a number of alternatives
are developed at greater length.

The Problem

There is a curious disconnect in climate change discourse,
between explanations of the causes of global climate change (GCC) and
discussions of possible solutions. On the one hand, it is widely acknowledge
that the primary causes of climate change are economic and demographic growth.
As the 4th Assessment Report from the Intergovernmental Panel on Climate Change
(IPCC) succinctly puts it: “GDP/per capita and population growth were the main
drivers of the increase in global emissions during the last three decades of
the 20th century . . . At the global scale, declining carbon and energy
intensities have been unable to offset income effects and population growth
and, consequently, carbon emissions have risen” (Climate Change 2007:
Mitigation (2007),Technical Summary, p.107). On the other hand,
most proposals for climate change mitigation take population growth and
economic growth as givens, beyond the realm of policymaking, and focus instead
on technological efficiency improvements as the sole means of reducing green
house gas emissions.

Climate scientists speak of the “Kaya Identity”: the four
primary factors which determine overall greenhouse gas emissions. They are
economic growth/per capita, population, energy used to generate each unit of
GDP, and greenhouse gases generated per unit of energy. Over the past four
decades, improvements in energy and carbon efficiency have been overwhelmed by
increases in population and wealth. Here are the numbers, again according to
the IPCC: “The global average growth rate of CO2 emissions between
1970 and 2004 of 1.9% per year is the result of the following annual growth
rates:

Crucially, the IPCC’s projections for the next several
decades see a continuation of these trends. More people living more affluently
mean that under “business as usual,” despite expected technical efficiency
improvements, greenhouse gas emissions will increase between 25% and 90% by
2030, relative to 2000 (ibid., p.111). If we allow this to occur, it will
almost surely lock in global temperature increases of more than two degrees
Centigrade over pre-industrial levels, exceeding the threshold beyond which
scientists speak of potentially catastrophic climate change. Following this
path would represent a moral catastrophe as well: the selfish
over-appropriation and degradation of key environmental services by the current
generation to the detriment of future ones, by rich people to the detriment of
the poor, and by human beings to the great detriment of the rest of the living
world.

A reasonable person reading the IPCC report and subsequent
scientific literature on climate change would likely conclude that we are
bumping up against physical and ecological limits. Given the dangers of
catastrophic GCC, a prudent and moral response might be: “Wow! This is going to
be hard. We need to start working on this problem with all the tools at our
disposal. Increasing energy and carbon efficiency, to be sure. But also
decreasing the pursuit of affluence and overall consumption; and stabilizing or
reducing human populations. Maybe in the future we can grow like gangbusters
again, maybe not. But for now, we need to make fewer demands on nature and see
if even our current numbers are sustainable over the long haul. After all, our
situation is unprecedented—7 billion people living or aspiring to live in
modern, industrialized economies—and there is no guarantee that we aren’t
already in ‘overshoot’ mode.”

Such convictions would only be strengthened by considering
further evidence of global ecological degradation from the recent Millennium
Ecosystem Assessment (MEA), including the depletion of important ocean
fisheries, accelerating soil erosion, ongoing species extinctions throughout
the world, the growth of immense “dead zones” at the mouths of many great
rivers, and more. According to the MEA, humanity is currently degrading or
utilizing unsustainably fifteen of twenty-four key ecosystem services.

However, neither GCC nor any of these other problems have
led to a widespread re-evaluation of the goodness of growth. Regarding GCC, we
have seen a near-total focus on technological solutions by politicians,
scientists, the general public, and even environmentalists. I contend that this
is a serious mistake. Because business as usual with respect to consumption and
growth almost surely cannot avoid catastrophic GCC or meet our other global
ecological challenges, we need to consider a broader range of alternatives that
include slowing or ending growth. Failure to do so, will likely mean failure to
avoid catastrophic global climate change.

The Wedge Approach

Of the many possible examples of mainstream approaches to
climate change mitigation that we might consider, let us look at one of the
most comprehensive, rigorous, and influential, Stephen Pacala and Robert
Socolow’s “wedge” approach, first presented in “Stabilization Wedges: Solvingthe Climate Problem for the Next 50 Years with Current Technologies,” Science 305 (2004): 968–972. Recent research and even a downloadable version of the
“Carbon Mitigation Wedge Game” can be found at the website for the Carbon Mitigation Initiative.The
wedge approach is a heuristic designed to help compare alternative mitigation
schemes. Pacala and Socolow’s stated goal, in the face of numerous mitigation
proposals and skepticism about whether any of them could succeed, was to
provide a practical road map of choices that could facilitate successfully
addressing the problem of GCC.

Each wedge in Pacala and Socolow's “stabilization triangle”
repre­sents a technological change which, fully implemented, would keep one
billion metric tons of carbon from being pumped into the air annually, fifty
years from now. It would also prevent twenty-five billion metric tons of carbon
from being released during the intervening fifty years. The authors figure
eight such wedges would have to be implemented to keep atmospheric carbon from
doubling and pushing past potentially catastrophic levels during this period.
In order to fully address GCC, in the next fifty years, humanity would
have to move to an economy where human carbon outputs did not exceed carbon uptakes
in natural systems. The wedge approach buys us time and (allegedly) begins the
transition toward such an economy.

Pacala and Socolow provide fifteen possible “wedges.” These
include: doubling the fuel economy of the world auto fleet; replacing coal plants
generating 1,400 gigawatts of power with natural gas plants; implementing
carbon capture and storage at coal plants generating 800 gigawatts or at
natural gas plants generating 1,600 gigawatts; deploying 2 million
1-megawatt-peak windmills (50 times current capacity); and substituting biomass
fuel for fossil fuel by using 250 million hectares (1/6 of world cropland!) for
ethanol production.

A strength of the wedge approach is that it allows us to
specify the costs and benefits of different courses on climate action and thus
choose intelligently between them. So far this has mostly meant asking which
wedges are cheapest economically. But the approach could also allow us to
compare alternatives based on environmental impacts, equitable sharing of costs
and benefits, dangers of unintended side-effects, whether the alternatives
increase or decrease humanity’s immoral hogging of resources that other species
need to survive, or whatever criteria we deem relevant.

A weakness of the wedge approach, as it has been developed
so far, is that the wedges proposed focus almost exclusively on technological
fixes and efficiency gains. Not that there’s anything wrong with such efforts.
But given that the primary causes of global climate change are unremitting
economic and demographic growth, it makes sense to consider “alternative
wedges” that target consumption reductions, population stabilization, and the
moderation of economic growth itself.

Like most discussions of climate change, the wedge approach
as developed to date simply takes for granted that our goal should be to
accommodate more consumption by more people with less
environmental impact. This goal is impossible to meet. Endless growth is
impossible in a finite physical system, such as planet Earth. Our failure
to consider limits to growth seems likely to lead to catastrophic GCC and to
further delay in humanity’s necessary transition to ecological sustainability.

I present these wedges as a supplement to Pacala and
Socolow’s techno-efficiency wedges, not as an (exclusive) alternative to them.
In fact, I think the best mix of measures to prevent catastrophic climate
change—best in terms of their justice, efficiency, and contribution to genuine
sustainability—will include a mix of efficiency improvements and policies to
reduce consumption, production and population.

These alternative wedges are works in progress, with some
more well-worked-out than others. In the sub-pages below, I present some of my
most recent calculations and thoughts regarding them. I would greatly
appreciate any comments or criticisms. Feel free to write to me at philip.cafaro@colostate.edu.

In the end, the case for deploying these alternative wedges
rests on complex empirical and ethical judgments. But so, I think, does the
case for not deploying them and instead focusing primarily on
techno-fixes, the currently favored approach.